Objective: To study morphometric and structural connectivity changes in the mesocorticolimbic pathway associated with the occurrence of impulse control disorders in Parkinson’s disease.

Background: Impulse control disorders (ICD) are frequent and disabling non motor side effect in Parkinson’s disease. Even though the main risk factor of their onset is the dopamine replacement therapy – mainly dopamine agonists -, structural changes in the meso cortico limbic pathway may confer an increased risk for development of ICD.

Method: Forty PD patients with (n=20 PD-ICD) and without (n=20 PD-nICD) ICD, and 20 healthy controls (HC), matched for age and sex were analysed. They all underwent 3T magnetic resonance morphologic and diffusion tensor imaging. For all patients, clinical data and antiparkinsonian medication dosages were collected. Whole brain measures of volumes, fractional anisotropy (FA) and mean diffusivity (MD) were analysed.

Results: We found that grey matter total volum of both hemispheres were significantly lower in the PD than in the HC (p≤0.05), with a volum significantly more elevated in the PD-ICD compared with the PD-nICD(p≤0.05),. We did not find any volume differences of the limbic subcortical structures.
FA was significantly elevated in the PD-nICD compared with the PD-ICD (qFDR = 0.003), in two symmetric periventricular white matter tracts (the stria terminalis), the left anterior cingulate gyrus (qFDR= 0.04), the right superior parietal lobule (qFDR= 0.02), and few small cortical regions. Analysis of MD between the two PD groups revealed that MD was significantly higher in the PD-ICD than in the PD-nICD group in the same periventricular with matter tracts (p=0.03).

Conclusion: Decreased FA and increased MD are evidences for an alteration of the neural network in white matter. In our study, PD-ICD patients appear to have alterations of the structural connectivity within the stria terminalis wich is part of the mesocorticolimbic pathway. We also found evidence in the same group for a larger alteration of the neural network within other regions of the limbic system, as in the anterior cingulate cortex.
This alteration of structural connectivity within the mesocorticolimbic pathway may be the trigger of the occurrence of ICD in PD patients.

« Back to MDS Virtual Congress 2020

MDS Abstracts - https://www.mdsabstracts.org/abstract/impulse-control-disorders-in-parkinsons-disease-a-whole-brain-morphometric-and-diffusion-tensor-study/